Caster Semenya, the two-time Olympic champion from South Africa in the 800 meters, said Monday that she would legally challenge track and field’s world governing body, attempting to block a much-debated rule that seeks to limit the permitted testosterone levels in female athletes in races over certain distances.

Semenya, 27, called the rule, which is scheduled to go into effect in November for races from 400 meters to one mile, medically unnecessary, “discriminatory, irrational, unjustifiable” and a violation of the rules of sport and universally-recognized human rights.

Semenya said the rule stigmatized women who do not conform to perceived notions of femininity and permitted discrimination against them. She argued that she should be able to compete the way she was born without “being obliged to alter her body by any medical means,” according to a statement released by her lawyers.

Her legal challenge is being made to the Swiss-based Court of Arbitration for Sport, a kind of Supreme Court for international sports.

“I am very upset that I have been pushed into the public spotlight again,” Semenya said in her first extensive remarks about the rule since it was announced in April.

“I don’t like talking about this new rule,” she said. “I just want to run naturally, the way I was born. It is not fair that I am told I must change. It is not fair that people question who I am.”

She continued: “I am Mokgadi Caster Semenya. I am a woman and I am fast.”

She called the new rule objectionable because it would force some women with no prior health complaints to undergo hormone treatment to lower their naturally-occurring levels of testosterone. This would be done, her lawyers said, in “the absence of support by the available science.”

Semenya is equally concerned, according to her lawyers, that the rule continues “the offensive practice of intrusive surveillance and judging of women’s bodies, which has historically haunted women’s sports.”

The new rule is an attempt by track’s governing body, the International Association of Athletics Federations, to reinstate regulations governing female athletes with elevated testosterone levels.

On Sunday, the I.A.A.F. said in a statement that athletes with differences of sexual development could have a 5 to 6 percent advantage in performance over athletes with testosterone in the normal female range, “which is an enormous difference in events where milliseconds count. The effects are most clearly seen in races over distances between 400 meters and one mile, where the combination of increased lean body mass and elevated circulating hemoglobin appears to have the greatest combined impact.”

A spokesperson for the I.A.A.F. added, “We stand ready to defend the new regulations at the Court of Arbitration should we be asked to do so.”

In 2015, the Court of Arbitration for Sport suspended a previous rule, saying that the I.A.A.F. had not sufficiently quantified the performance advantage gained by having these raised levels. That case involved an Indian sprinter named Dutee Chand.

The governing body has since quantified the advantages, relying, in part, on a 2017 study it commissioned that was published in the British Journal of Sports Medicine. The study showed that women with elevated testosterone levels gained a competitive advantage from 1.78 percent to 4.53 percent in events like the 400 meters, the 400-meter hurdles, the 800 meters, the hammer throw and the pole vault.

The new rule would affect women with testosterone levels of five nanomoles per liter and above and would regulate eligibility for major international competitions like the Olympics and world championships.

Most women, including elite female athletes, have natural testosterone levels of .12 to 1.79 nanomoles per liter, the I.A.A.F. said, while the normal male range after puberty is much higher, at 7.7 to 29.4 nanomoles per liter.

No female athlete would have natural testosterone levels at five nanomoles per liter or higher without so-called differences in sex development or tumors, the I.A.A.F. said. In effect, it is saying that athletes with such elevated levels are biologically male.

Individuals with differences in sex development, or D.S.D., can have high levels of testosterone that “extend into and even beyond the normal male range,” the I.A.A.F. said in April in announcing its new rule.

Approximately seven of every 1,000 elite female athletes in track and field have elevated testosterone levels, about 140 times the general population, the I.A.A.F. said. Most compete in events from 400 meters to the mile, races that require an acute combination of speed and endurance.

Under the new rule, an athlete who does not want to lower her testosterone levels would face several difficult choices: change the distance at which she races to beyond one mile; compete against men; enter competitions for so-called intersex athletes, if any are offered; or give up her eligibility to perform in the most prestigious competitions like the Olympics.

The I.A.A.F. said it was not accusing intersex athletes of cheating or requiring them to undergo surgery. Sebastian Coe, president of the I.A.A.F., said in April that the rule was simply meant to level the playing field “to ensure fair and meaningful competition.”

A version of this article appears in print on , on Page B7 of the New York edition with the headline: Olympian Challenges Testosterone Rule. Order Reprints | Today’s Paper | Subscribe